Data Members and Properties of Netbeans IDE 7.0

8/6/2019 Data Members and Properties of Netbeans IDE 7.0

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NetBeans IDE


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After studying this lesson the students willbe able to:

Identify, name and state the usage of

the different components of theNetBeans IDE.

Identify and name the various methodsand properties associated with thevarious form controls

Create simple applications in Java usingNetBeans IDE.


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NetBeans IDE allows us to develop applicationsby dragging and positioning GUI componentsfrom a palette onto a container. The GUI builderautomatically takes care of the correct spacingand alignment of the different componentsrelative to each other. The JFrame acts as acontainer for the elements like the JLabel,JButton, JTextArea and allows direct editing of

their associated properties at the design time andrun time. The related methods are used in thecode to develop applications for a specific task.The concept of variables and control structuresare used to simplify the code of the applications.


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It can be used to create java applications very easily

using the efficient GUI builder. Let us quickly recap

the different components of the NetBeans IDE:


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1) Title Bar

2) Menu Bar with pull down menus

3) Toolbars

4) GUI builder: It is an area to place

components on the form visually. There

are two views of the GUI builder- theDesign View and the Source View. We

can switch over from one view to

another by simply clicking on the

source and design tabs directly abovethe Design Area.


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5. Palette: Palette contains controls orcomponents used to create GUI

applications.

6. Inspector Window: This window is usedto display a hierarchy of all thecomponents or controls placed on thecurrent form.

7. Properties Window: Using this windowwe can make changes in the properties

of currently selected control on the form.8. Code Editor Window: - It is the areawhere we write code for our javaapplication.


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Components

Components (also known as "widgets") are the basicinterface elements the user interacts with: jlabels,jbuttons, jtextfields etc. Components are placed on acontainer (like the jFrame). There are two types of

controls :

Parent or Container Control: They act as abackground for other controls. For example-Frame. When we delete a parent control, all its

child controls get deleted. When we move a parentcontrol all its child controls also move along with it.

Child Control: controls placed inside a containercontrol are called child controls. For example-TextField, Label, Button etc.


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Creating a New Project

The steps to create a new project are:

1. Select New Project from the File menu. Youcan also click the New Project button in the

IDE toolbar.2. In the Categories pane, select the General

node. In the Projects pane, choose the JavaApplication type. Click the Next button.

3. Enter the name of the project in the ProjectName field and specify the project location. Donot create a Main class here.

4. Click the Finish button.


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Project Window Showing Multiple Forms

Further each form can have one or more elements - some of which

may be visible and some invisible. The visible components are all

shown under the Frame Component and the non-visible

components are part of Other components.


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Drag and Drop Feature

We use the drag and drop feature of NetBeansto place components on the form to design aneffective interface for our applications. The firststep that we undertook while designing our

applications was adding a new jFrame form.

The jFrame is a window with Multiple Formsunder one Project Project Name, title, border,(optional) menu bar and is used to contain allother components placed by the user on theform. Some of the properties of the jFrameform are defaultCloseOperation and Title.


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Properties of jFrame Form

Any component of GUI front-end (the form itself and theswing containers and controls placed in the form) of anapplication is an object. Each of these objects belongs to itscorresponding class predefined in Java. For example, a

form is an object of JFrame class, all the textfields areobjects of JTextField class, and so on. Each object hassome properties, methods, and events associated with itusing which you can control the object's appearance andbehaviour.


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Properties, Methods and Events

Properties

Properties of an object are used to specify its appearance on the form. Forexample to set the background colour of a textfield you change itsbackground property; to set its font you change its font property; and so on.

MethodsMethods are used to perform some action on the object. For example todisplay something in a textfield you can use its setText() method, to extractthe contents of a textfield you can use its getText() method.

Methods can be divided into two categories getters and setters.

Getters are the methods which extract some information from theobject and return it to the program. Getters start with the word get.Examples of getters are: getText(), getForeground(), getModel(),isEditable etc.

Setters are the methods which set some properties of the object sothat the object's appearance changes. Setters start with the word set.Examples of setters are: setText(), setForground(), setModel() etc.


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Cont..

Events

Events are the actions which are performed oncontrols. Examples of events are: mouseClick,mouseMoved, keyPressed etc. When the userperforms any action on a control, an event happensand that event invokes (sends a call to) thecorresponding part of the code and the application

behaves accordingly.

After setting the properties of the jFrame we can startplacing components like jButton on the jFrame form. Abutton is a component that the user presses or

pushes to trigger a specific action. When the userclicks on the button at runtime, the code associatedwith the click action gets executed. The variousmethods and properties associated with the jButtonare summarized


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Properties

and

methods

ofjButton


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jTextField and jLabel

jTextField allows editing/displaying of a

single line of text. jTextField is an input

area where the user can type in characters

whereas a jLabel provides text instructionsor information. It displays a single line of

read-only text, an image or both text and

image. The various methods andproperties associated with the jTextField

and jLabel are summarized


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Properties and Method of jTextField


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Properties and Methods of jLabel


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When we had become familiar with the usage of jTextField and jLabel controls then

we developed an application in which we wanted to accept multiline input anddisplay multiline output. Well can you recall the name of the component. Exactly the

component is Text Area component. This component allows us to accept multiline

input from the user or display multiple lines of information. This component

automatically adds vertical or horizontal scroll bars as and when required during run

time. The various methods and properties associated with the jTextArea are

summarized


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Properties and Methods of jTextArea


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Properties of jPassword


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Radio Button and Check Boxes

We have used radio buttons when we wanted to provide theuser several choices and allowed him to select one of thechoices (the radio buttons belong to a group allowing the userto select single option). But radio buttons occupy a lot ofspace. Thus, in case of too many options we used Combo

boxes as they help save space and are less cumbersome todesign as compared to radio button.

We used check box and list when we wanted to displaymultiple options like selecting favourite sports or ordering

multiple food items in a restaurant. The list is a preferredoption over check box in situations wherever multiple optionsare required to be selected from a large number of known setof options as they help save space and are less cumbersometo design as compared to check boxes. The properties andmethods of jRadioButton are summarized below:


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Properties and Methods of jRadioButton


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Properties and Methods of jCheckBox

jCheckBox is a small box like component that is either marked or

unmarked. When you click on it, it changes from checked to unchecked or

vice versa automatically. The properties and methods of jCheckBox are

summarized below:


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Documents

Data Members and Properties of Netbeans IDE 7.0